Finally some DNA
It's official, no beer bottles left on our bench. On September 10, we completed the collection of 96 beers from your votes, from your shipments and from our sponsors. We put on our bench beers from 20 countries, see a map here.
We rotated each beer by hand for 5 minutes to resuspend any DNA-containing residue that may have been deposited on the bottom. Then, we untapped the beer, poured and mixed the beer inside a flask to remove some CO2 because the gas was interfering with the following step. Beautiful colors and tantalizing aromas!
Than, we had to isolate the stuff that contains DNA: the cells. We poured 50 mL of beer on conical tubes that were centrifuged for 10 minutes at high speed. The cells (yeast, bacteria, barley fragments etc.) would deposit on the bottom of the tube, something that we generally call "pellet".
We learned some lessons here: lagers were a nightmare to process because the pellet was unstable and lifted up, ales were much easier to handle. The contrary of what top fermentation and bottom fermentation would suggest.
Not all the beers have the same pellet, however we found pellet for our pipettes even in filtered beer: the filtration efficiency is never 100%.
Here our 96 pellets:
From the pellet, we are now extracting the DNA. We tested different protocols, and finally we found one that is working nicely. The major problem we had to face was that beer contains some inhibitors for the sequencing reaction, we were able to isolate DNA but there was some inhibitor carryover that stopped us for moving further.
Finally, we found the way to remove these inhibitors from DNA using a protocol adapted from stool DNA extraction. Stumbling on a stool is a sign of good luck in Italy.
We have now the DNA of 12 of the 96 beers and we are moving forward. Once we will have all the 96 DNA samples we will rent the sequencing machine and digitize the beers. We are in good company as you can read on Draft Magazine "Can we digitize beer's flavor?".
Thanks to your help we are moving forward, you will be the first to learn about the upcoming results. Like our facebook page for more granular updates. Cheers!
Gianpaolo and the BeerDeCoded team.